Internal-combustion heater with nozzle heating means



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INTERNAL-COMBUSTION HEATER WITH NOZZLE HEATING MEANS 2 Sheets-Shtl viihlir W.. www

Novf, 1948.

original Filed Nov. e, 194:5

Nov. 30, i948. L. A. WILLIAMS, JR

`IIIIJ.ERNALCMBUSIION HEATER WITH NOZZLE HEATING MEANS 2 Sheets-Sheet 2 Original Filed Nov. 6. 1943 Zahlt/lill? Patented Nov. 30, 1948 INTERNAL-YCOMBUSTION HEATER WITH NOZZLE HEATING MEANS Lynn A. Williams, Jr., Indianapolis, Ind., assignor to Stewart-Warner Corporation, Chicago, Ill., a corporation of Virginia Original application November `6, 1943, Serial No.

509,161. Divided and this application December 20, 1945, Serial No. .636,208

5 Claims. 1

My invention relates to internal combustion heaters of the type particularly adapted for, but not limited to, use in heating the cabins and other parts of aircraft.

This application is a division of my copending application Serial No. 509,161, filed November 6, 1943.

An object of my invention is to provide an internal combustion heater having new and improved means for preventing overheating of the nozzle during heater operation, and for heating this nozzle during the starting period. v

Other objects and advantages will become apparent as the description proceeds.

In the drawings:

Fig. 1 is a side view of a heater installation embodying my invention and showing parts cut away to illustrate details of construction;

Fig. 2 is a transverse, irregular sectional view taken on the line 2--2 of Fig'. l; and

Fig. 3 is a partial, sectional view of the nozzle assembly and is taken on the line 3-3 of Fig. 2.

I have illustrated my invention as comprising a heater casing I having its left-hand end attached to an air supply pipe I2 which leads to a ram, blower, or any other suitable source of air supply. The right-hand or outlet end of the heater casing i0 is connected t0 a duct I4 leading to an aircraft cabin or other space or spaces to be heated with Ventilating air furnished by the heater. It will be understood that the duct I4 may have one or more outlets and may be provided with any usual or desired arrangement of shutters for controlling flow of Ventilating air into the space or spaces supplied by the heater.

The casing l0 encloses a heat exchanger I6 which may be of any suitable type, but which is illustrated herein as being of the spiral type disclosed and claimed in the copending application of William C. Parrish, Serial No. 494,155, led July 10, 1943. A perforated cone I8 has its large end attached to the left-hand or inlet end of the heat exchanger l and forms a conical combusn .tionchamber 2i] supplying hot products of combustion to the heat exchanger. These hot gases Aow through a spiral gas passage in the heat to the -smaller end of the cone i8 andto the .cor-

responding end of a cylindrical shell 30, welded or otherwise suitably secured to the cone, and in eiect constituting a part thereof. This casting 28 is threaded, as indicated at 32, to receive a plug-like electrical igniter 34, having a resistance wire 36 in open communication with the interior of the cone I 8. This igniter is supplied with current through an insulated conductor 38 having one end attached to the igniter plug and the other end attached to a terminal l0 of a terminal bracket 42, havingoutwardly turned ends 44 attached to the casing I0 by rivets 46. The terminal plate or bracket 42 also has additional terminals 48 and 50.

A nozzle casting 52 is removably secured to the casing 28 by screws 54. This casing is threaded to receive a plug-like nozzle B, including a cylindrical strainer 58 for removing impurities from the fuel before this fuel enters the nozzle andr is discharged thereby into the combustion chamber in the form of a conical spray. The strainer 58 is located in a chamber 69 formed in the casting 52 and supplied with fuel through a restricted inlet 62. A stud 64 is threaded into a boss 66 provided by the casting 52. This stud projects through an opening in a cover S8 which is clamped against the left-hand end of the housing 24 by washer I0 and nut I2 screwed onto the end of the stud 64.

The cover 68 and housing 24 provide a combustion air space 'i4 surrounding cone I8 and the nozzle and igniter assembly secured thereto. Air

from the combustion air space 'M passes through the perforations in the cone I3 to mix with the fuel delivered by the nozzle 56 and form the combustible mixture which is burned in the combustion chamber 20. Air for the combustion air space 'i4 is furnished by a combustion air supply pipe indicated generally by the reference charac ter 16. This pipe includes a metal elbow 'I8 attached at one end by a coupling to a nipple 82 welded or otherwise secured to the housing 24 and in open communication with the interior of this housing. rlihe `other end of the elbow 'i8 is clamped to one end of a short section of Iiexible hose Si, the other end of which is clamped to a rigid pipe 82 leading from any suitable source lof combustion air supply.

.nipple 82, coupling and adjacent portion 'of ithe elbow 'I8 of the combustion air supplypipe.

`pipe adjacent the nozzle.

This elbow 18 is provided with a short sleeve 88 Welded thereto and this sleeve snugly fits about the copper tubing 85 adjacent a point where it passes through a wall of this elbow. One end of the copperf tubing 86 is connected by a coupling 90 to a second section of copper tubing 92-leading to a solenoid valve 94 connected to a fuel supply pipe 96 leading from a fuel pump or any other suitable source of fuel under pressure.

The solenoid valve 94 is strapped toa bracket 98 suitably secured to the casing l0 and this bracket is illustrated as providing a clip forming an intermediate support for the copper tubing. A conductor |92 connects the solenoid valve to the terminal 48. A third conductor |04is illustrated as being connected to the terminal 50 and this conductor may lead to any additional, control means not shown. It will be understood that suitable circuits are connected to the terminals 40, 48 and 5U for supplying current to these terminals and such circuits may include thermal switches, manual switches and. other usual control elements.

Particular attention is called to the fact that the fuel supply line for the nozzle 56 is surrounded by the air inlet pipe where this line extends across the Ventilating air space between the casing Ill and the housing 24. This is important in that it 4prevents contamination of the Ventilating air by Any fuel L fuelleaking from this fuel supply line. which leaks from a portion of the fuel supply line adjacent the Ventilating air passage between the heater casing l0 and housing 24 passes into the combustion air space 'i4 and vaporizes to mix with the combustion air4 delivered to the combustion chamber through the openings in the cone i8. Attention is also called to the fact that the electrical conductor 38 for the igniter 34.also enters the housing 24 by way of the; combustion air supply line. The elbow 'I8 has a grommet 106 surrounding an opening through which this conductor extends. This grommetclosely fits the conductor to prevent or minimize leakage of combustion air from the combustion air supply pipe at this point. The points at which the electrical conductor 38 and copper tubing 86 pass through the wall of the elbow 18 are outside of the ventilating air stream so that slight leakage of cornbustion air at these points is immaterial, as such leakage will not tend to contaminate the ventilating air.

The combustion air flowing through the oombustion air supply pipe and chamber 14 connected therewith will prevent overheating of the fuel owing to the nozzle B and will prevent vapor l lock occurring in the section of the fuel supply Where extreme cooling of this portion of the fuel supply line is desired, the combustion air supply pipe should be connected with a source of unheated air. However, where a heavy fuel is used or where, for other reasons, vapor lock is not a problem, the combustion air supply pipe may, if desired, be supplied with heated air fromthe duct I4 or from any other suitable source.

A feature of my invention lies in the particular arrangement of the fuel nozzle and igniter relative to each other and to the combustion chamber so that heat from the igniter is transmitted to the nozzle during the starting period, but relatively littleheat is transmitted to the nozzle from the combustion chamber while-the heater is in normal operation. The castinglZB is preferably made of material having a high heat conductivity such as, for example, brass; This casting supports the igniter plug 34 and transmits heat therefrom to a point adjacent the end of the nozzle 56 which is surrounded by a tubular-like portion of this casting. This construction functions to conduct heat to the nozzle both by radiation from theadjacent portion of the casting 28 to the nozzle and by conduction through the nozzle casting 52 into which the nozzle is threaded. It will be understood that the igniter 34 is cut olf from its source of current by the usual thermostatic switch after the heater has attained normal operating temperature so that heat is transmitted from the igniter to the nozzle only during the starting period.

The combustion air entering the interior of the housing 24 and the cover 58, which is in sealing engagement therewith, surrounds the cone I8 and nozzle and igniter assembly and absorbs heat therefrom during normal heater operation; furthermore, the nozzle is indirectly attached to the small end of the cone i8 through castings 52 and 28 and the former casting is preferably made of cast iron, or other material having a relatively low coefficient of heat conductivity. Only a small part of the casting 28 is directly exposed to the combustionA chamber, and a large part of the heat absorbed by this casting is conducted to the igniter plug 34 and shell 3D and dissipated therethrough; furthermore, the small end of the cone I8 is surrounded by a large body of combustion air which is flowing to the combustion chamber through the perforations in this cone, so that the end of the cone attached to the casting 28 is the coolest part of this cone. All of these factors combine to prevent excessive heating of the nozzle during burner operation, and thereby to prevent cracking of the fuel passing therethrough.

While I have illustrated and described only a Asingle embodiment of my invention, it is to be understood that my invention is not limited to the particular details shown and described, but may assume numerous other forms, and that my invention includes all modifications, variations and equivalents coming Within the following claims.

I claim:

1. Ah internal combustion heater of the class described, comprising a perforated cone providing a combustion chamber, means for supplying combustion air to the exterior of said cone, a nozzle indirectly connected to said cone for supplying fuel to said combustion chamber, a rst part of high heat conductivity interposed between said nozzle-and cone and in heat conducting relation to the small end of said cone, a resistance igniter for heating said rst part, said igniter being mounted in heat transmitting relation to said first part and having a portion positioned for igniting fuel supplied to said combustion chamber, and a second part of relatively low heat conductivity connecting said nozzle with said first part.

.2. A burner of the class described, comprising -a perforated cone providing a combustion chamber, av member of higher heat conductivity than said cone secured to the small end of said cone, a nozzle having a part surrounded by said member and aligned with said cone for supplying fuel to said combustion chamber, a support for said nozzle attached in heat transmitting relation to said member, said support providing less total heat conductance than said member, an electrical resistance igniter mounted on said member in heat-transmitting relation thereto, and having a'portionpositioned for igniting fuel supplied to said combustion chamber, means providing an air chamber surrounding said cone member, nozzle and igniter, and means for supplying combustion air to said chamber.

3. A burner of the class described, comprising a perforated cone providing a combustion chamber, a member of high heat conductivity having a tubular part secured to the small end of said cone, an igniter plug of the resistance type mounted in said member at one side of said tubular part and having a portion positioned for igniting fuel supplied to said combustion chamber, a second member of relatively low heat conductivity attached to said first member, a fuel nozzle mounted in said second member and extending into the tubular part of said first member in spaced relation to the inner Wall thereof, and means for supplying fuel to said nozzle.

4. A heater of the class described, comprising a casing, a heat exchanger located in said casing, a perforated cone attached to one end of said heat exchanger an-d providing a combustion chamber for supplying hot gases to said heat exchanger, a, housing surrounding said perforated cone, a heat-conducting member attached to the housing provi-ding a combustion air chamber surrounding said cone, nozzle, igniter and first and second members, said housing and cover being located in said casing in spaced relation thereto, and means for supplying liquid fuel for said nozzle, combustion air for said combustion chamber, and electricity for said gniter.

5. An internal combustion heater' of the class described, comprising a perforated cone providing a combustion chamber, means for supplying combustion air to the exterior of said cone, a nozzle indirectly connected to the small end of said cone for supplying fuel to said combustion chamber, a rst part of high heat conductivity interposed between said nozzle and cone and in heat conducting` relation to said cone, electrical heating means for said first part, and a second part of relatively low heat conductivity connecting said nozzle with said rst part.

LYNN A. WILLIAMS, JR.

REFERENCES CTED The following references are of record in the file of this patent:

UNITED STATES PATENTS FOREIGN PATENTS Country Date Great Britain Oct. 7, 1926 Number Number 

